Roofing tools (e.g., pneumatic roofing tools) are used to drive roofing nails into workpieces such as shingles to secure the shingles to the underlying wood substructure. Such roofing tools typically have a magazine that holds a supply of nails. The nails are typically collated by being spot-welded or otherwise affixed at their shanks to a pair of flexible metal wires or by being embedded in or adhered to a plastic or paper collating strip. Existing nail magazines typically are configured to receive a supply of nails arranged in either a stick or a coil arrangement.
Because the nails in a stick-type magazine are arranged in a linear fashion, a spring-biased or otherwise tensioned feed mechanism can be used to urge the stick-shaped collation of nails into the fastener drive track located in the nose portion of the tool by pushing the stick of nails from the rear thereof. In a coil magazine arrangement, on the other hand, the nails are arranged in a spiral, with the nails being fed into the fastener-drive track from the leading succession of fasteners in the coil. Because the nails are arranged in a spiral or coil configuration, a spring-biased or otherwise tensioned pusher apparatus by means of which the supply of nails is urged toward the fastener-driving track from the tail end of the supply would not be suitable. Therefore, roofing tools with coil-type magazines typically have a reciprocating feed mechanism that is operatively disposed along the feed track between the magazine and the fastener-driving track. Upon actuation of the fastener-driving tool, the feed pawl of the reciprocating feed mechanism retracts and “catches” a following nail in the strip or collation of nails; upon its return stroke, the feed pawl pulls the succession of nails forward, toward the nose portion of the roofing tool to advance the nails and feed the leading nail successively into the drive track.
As the feed pawl reciprocates, there is a tendency for it to “carry” the nails away from the fastener-driving track as it retracts to grab a nail. Therefore, a check pawl typically is provided in the reciprocating feed mechanism to prevent the strip of nails from being pushed backward as the feed pawl retracts. The check pawl may, for example, be provided within the fastener feed track access door—the door by means of which access is gained into the nose portion of the tool, e.g., to load the nails into the nose portion of the tool at the beginning of a given supply—in generally opposing relationship to the feed pawl.
As the nails within a given strip of nails are used up and the supply diminishes, less nails remain within the fastener feed track to properly position and hold the nail that is about to be driven within the drive track. Therefore, various configurations have been developed to hold the last nail to be driven within the tool. For example, certain tools have used a small magnet on the side of the drive track to hold the last nail in position. However, such a device has not proven to be very effective and reliable during extensive field usage. In particular, it has been found that about half of the time, the last nail will not be held within the drive track and will simply drop on the roof. That is undesirable because the operator will have to clean up after the job, he may injure himself by stepping on the dropped nails, and/or it is wasteful of nails.
In addition to these drawbacks or disadvantages, some fastener-driving tools are known in which there is no effective mechanism to indicate to the operator that no fasteners (e.g., nails) remain in the tool. In that case, the operator can keep operating the tool without fasteners, which causes the tool driver tip to strike and dent the roofing shingle or other workpiece.